Is there a way to compute residuals multi-threads, like Solver::Options::num_threads for jacobians ?

[3658...@qq.com]

I know that "Solver::Options::num_threads" can compute jacobians by multi-threads very efficiently and it works pretty well in my program.

But I found in my summay that now the residual computation time is dominant. I wonder if there is a way similar that can compute residuals by multi-threads too ?

[Sameer Agarwal]

The same threading mechanism is used for jacobian and residual computation.

Sameer

On Fri, Dec 29, 2017 at 10:09 PM <3658...@qq.com> wrote:

I know that "Solver::Options::num_threads" can compute jacobians by multi-threads very efficiently and it works pretty well in my program.

But I found in my summay that now the residual computation time is dominant. I wonder if there is a way similar that can compute residuals by multi-threads too ?

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[3658...@qq.com]

Here is what I found on the website:

int Solver::Options::num_threads

Default: 1

Number of threads used by Ceres to evaluate the Jacobian.

Thanks, Do you mean that it can also evaluate residuals? If thats the case, I would suggest make it clear on the API document too.

[Sameer Agarwal]

yes that is what I mean. 

residual evaluation is usually dominated by the jacobian evaluation that we did not think it was worth mentioning. I will update the docs.

Sameer

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[3658...@qq.com]

Thank you. Because I have thousands of laser points and so many blocks. So adding up the residuals also took lots of time. After setting the option, time of jacobian evaluation is less than residuals evaluation. Thats why I wonder.

[Sameer Agarwal]

Status::FullReport() or it didn't happen :)

Sameer

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[Sameer Agarwal]

Summary::FullReport() I mean.